text: Whatever process is used to make the tableting blend, the process of making a tablet by powder compaction is very similar.  First, the powder is filled into the die from above.  The mass of powder is determined by the position of the lower punch in the die, the cross-sectional area of the die, and the powder density.  At this stage, adjustments to the tablet weight are normally made by repositioning the lower punch.  After die filling, the upper punch is lowered into the die and the powder is uniaxially compressed to a porosity of between 5 and 20%.  The compression can take place in one or two stages (main compression, and, sometimes, pre-compression or tamping) and for commercial production occurs very fast (500–50 mg per tablet). Finally, the upper punch is pulled up and out of the die (decompression), and the tablet is ejected from the die by lifting the lower punch until its upper surface is flush with the top face of the die.  This process is repeated for each tablet.
  Common problems encountered during tablet manufacturing operations include:
  * Fluctuations in tablet weight, usually caused by uneven powder flow into the die due to poor powder flow properties.
  * Fluctuations in dosage of the Active Pharmaceutical Ingredient, caused by uneven distribution of the API in the tableting blend (either due to poor mixing or separation in process).
  * Sticking of the powder blend to the tablet tooling, due to inadequate lubrication, worn or dirty tooling, or a sticky powder formulation
  * Capping, lamination or chipping.  This is caused by air being compressed with the tablet formulation and then expanding when the punch is released: if this breaks the tablet apart, it can be due to incorrect machine settings, or due to incorrect formulation: either because the tablet formulation is too brittle or not adhesive enough, or because the powder being fed to the tablet press contains too much air (has too low bulk density).
  * Capping can also occur due to high moisture content.
  Consequently, permanent consistency checks are required during the manufacturing process.